Oh yeah, el Mariachi,
the main character,
has a really cool gun case in the form of a guitar case.

The greatest obvious
benefit of a converted guitar case
is that it could be a sturdy and secureable gun case
that is not so obviously a gun case.
Most gun cases might as well have tall yellow letters on
the side screaming
GUN CASE!

Wouldn't it be an interesting project to build one?

A local pawn shop had a hard-shell Ovation guitar case
just barely big enough for the 44-inch M1 Garand
maximum dimension from muzzle to bottom of butt plate.
I snapped it up for about $30, a fraction of
the price of a new one, and brought it home.

It was lined with groovy electric blue Yeti fur.

Bright blue!

This is no surprise because everyone knows that
the Himalayan Yeti is a hybrid of
Wookiees
and
Smurfs.

As opposed to the Sasquatch, which is just a hoax.

+

=

YETI

The blue fur was worn through in places.

Yeti fur ain't what it used to be.

A little exploratory cutting revealed that the blue fur
was bound to a black fairly rigid plastic layer,
and its slick back side was against a dense polystyrene foam
forming the case's interior shape.

The plan eventually became:

Remove the blue fur from the bottom,
the main body of the case.

Trim the existing foam as needed to allow the Garand
to fit into the case.

Replace one of the latches to provide a secure and
lockable case latch.

Add that spray-in expanding foam as needed to
basically fill the bottom case flush with its
metal rim.
The original foam is some similar expanding material,
but it's a little denser and more rigid than the
spray-in foam you get at the home improvement store.
So trim the original as needed before proceeding!

Cut the resulting blended foam volume as needed
to produce fitted compartments for the Garand
and some pistols.

Cover the foamed bottom with felt.

All the foam in the main body of the case had to be exposed,
which meant that the blue fur in the bottom half had to
come out.

Here it is with all the main body fur removed.

And doesn't that sound like some sort of strange
yetirotica reference?

Here is a Garand laid in place.
It's 44" from muzzle to butt plate, so it barely fits this
case in terms of length.
But of course it doesn't go into the case,
at least not yet.

I needed to trim notches for the muzzle and butt plate
at either end of the case.
Then, two more notches for where the stock and barrel
cross two molded cross-pieces originally intended
for the neck of a specific guitar design.

Now it fits, at least as far as going into the case so
the lid could be closed.

Before going any further, the very lame latches
need attention.
Really, partial replacement.
The plan is to replace this central latch next to the
carrying handle and near the center of gravity
with a serious cabinet latch with a hasp for a padlock.

Brass 10-24 hardware will be used to mount the
latch pieces, with the 10-24 machine screws passing
through the latch, the case wall, and aluminum plates
on the interior face of the case wall.

The problem is that the metal rim gets in the way.
Some spacers are needed on the exterior.

It will look much classier with that aluminum sheet
in a beveled wrapper of copper flashing,
material I already had on hand for some other projects.

Here is that new latch in place on the case main body,
and with the lid securely cinched into place.

The copper still needs a final cleaning with #0000
steel wool in this picture, before an application
of polyurethane varnish to keep that bright
copper and brass look.

Just be glad that I didn't build the entire case from
scratch out of mahogany-stained luan underlayment,
malachite pattern laminate, and brass and copper.
Don't think that I wasn't tempted.
Seriously.

And speaking of bulky over-design
and just barely man-portable weight,
there are before and after weight measurements
at the end of this page.
It's not as bad as you might think.

Two button-like "feet" showed the folly of relying
on the plastic case for structural integrity.

Ovation, what were you thinking?

Some relatively soft aluminum sheet was cut to
approximately 2.5" x 7",
bent to shape and slid into place
between those feet and the main foam body.
The added aluminum sheet is visible here between the
aluminum rim of the case body and the cardboard strip
between the case body and the foam.

Now the feet can actually bear some weight.

A smaller similar plate was bent and pressed into place
at the muzzle end as preventative structural bracing.

On to the foaming!

Very important first step —
wear rubber gloves and do this in an area where you don't
terribly mind getting extremely sticky foam stuck to things.
It should also be the standard well-ventilated area:
no open flames, no breathing of the concentrated fumes
by man or beast, etc.
For example, a concrete balcony with brick walls.
Make sure you have a steel brush handy
to remove errant foam globs the next day.

I initially tried taping garbage bag material across the rim
of the bottom half and filling it with the supplied thin
nozzle pushed through the plastic.

That did not work.

I removed the plastic sheet and simply sprayed the foam
into the large tub shape to fill it with coils of the
nasty sticky expanding foam as you see here.
I did not use the screw-on plastic tube nozzles.

Just invert the can and bend the short nozzle on the can
valve so it comes out like the Devil's own cake frosting.
Make sure to only spray it with the nozzle down,
otherwise you risk losing propellant and not driving out
expanding foam.

I used
Fill and Seal Expanding Foam Sealant
from the Dow Chemical Company, based on the
highly technical reason that it was the cheapest.
It comes in 12 ounce (340g) cans and
it claims to expand to about 3X can volume.
That seemed about right.

Dow's
"Great Stuff" Big Gap Filler
Expanding Foam Sealant
is a newer product that might be better.
It is specifically designed to fill larger gaps
in home insulation projects,
or in the case of this project,
fill the needed volume with fewer cans and lighter
resulting weight.

An important concern is the chemical environment within the
case when it's finished.
The expanding foam seems to be full of organic chemicals,
some of them somewhat nasty (and most of them extremely
sticky!), but no water-based anything.

That's good.

I had never used this material before,
so I didn't know how much I needed.
I described the project to the guy at the hardware store
as a toolbox, not wanting to seem too nutty.
I now think he assumed I meant something like putting a
circular saw into a case in which it barely fits.

To be fair, this might be a somewhat unusual application.

I used three cans.

Important — while you're at the hardware store
you should read all of the cans of expand-o foam,
even the expensive ones you don't plan to buy.
It doesn't seem like any one container tells the
entire story about how to use expanding foam.
Other important details include:

Only spray inverted (nozzle lowest),
or at least that's an issue with some can designs.

Time to form an initial skin (30 seconds or so)
and time to fully cure
(8 hours seemed to be the consensus).

The cans are one-use-only.
There is no using part of a can now
and the rest of it later.

Cleanup is impossible,
except for what you can do with a wire brush.
Wear rubber gloves and old clothes.

I knew that some areas only needed partial filling.

The barrel of the M1 would occupy most of the middle
of the neck.
I could judge where filler was needed
by the notches I had carved into the original foam.

I needed a little in the bottom of the neck
but only needed to fully fill it along either side.

The main "bowl" for the guitar body needed to be mostly
filled, but again a narrow area through the center would
just need to be cut out eventually.

OK, there's a nasty gooey foamy mess.

Leave it alone and let it cure for 8 hours or more.

Here it is the next day.

What a gruesome looking mess.

But it has cured.

Now it's time for the initial trimming — some with
the sharp box cutter knife seen in other pictures,
some with this extremely dull large kitchen knife.

Despite its extreme dullness, it can cut this stuff.

The large blade helps to get a more planar cut.

Here I have sliced the foam so that everything is below
the surface formed by the metal band around the lower
main part.

Well, a very rough approximation to that surface....

Lay the Garand where it should go and trace around it
with a marker.
Here is that crime-scene style result.

After some cutting and carving using just the sharp
knife, the Garand fits!

Carefully think through what you're doing with
the cutting.

You can cut more or less straight down along that
traced line with the blade extended to the
appropriate length.

Most of the perimeter of this object as it lies on
its side is round.
Cylindrically curved edges of the butt stock,
cylindrical shapes of the rear hand guard and oval
shape of the forward hand guard, and so on.

Also consider the thickness of your marker and whether
you held it vertically (drawing an outline outside the
real profile) or tilted it to correct and draw the line
directly under the real profile.
Your line is probably outside the real profile at least
by a little, even if you tilted the marker as you drew.

So, the blade can be tilted so the cut intersects the
drawn line and the blade tip is slightly toward the
object axis.

The result of that would be a pit with slightly sloping
sides, just big enough for the traced object.

That is, once you manage to cut the floor of the cutout.
The trickiest part is getting the cutout floor roughly
horizontal.

Now repeat for some pistols.

Trace, then carve....

And multiple custom-fitted compartments!

Clockwise from left:

FEG PA-63,
or
Fegyver És Gépgyàr PA-63,
a Hungarian clone of a Walther PP.
It has a Makarov-style "thumbrest" left grip panel,
but that just means you carve a corresponding
divot into the foam.
It shoots
9x18mm Makarov.

You will have plenty of foam scraps at this point.
Find suitably sized and shaped ones to jam into any
small voids.
I had some voids below the Garand cutout
as that was getting down into the layers of foam
formed by my initial failed experiment
in foaming through a plastic sheet.
I had gotten most of one can's worth of foam into the case
that way, but it was erratically scattered around
and had partially cured by the time I got around to
going to the store to buy a second and third can of foam
and removing the plastic sheet.

I used a little plastic packing tape in places to hold
the scraps in place.
For example, those larger voids right at the case
body-neck transition.

I also used it to reinforce the thin foam walls between
the Garand stock and the two pistol butts.

Now for the felt lining.

This gets somewhat frantic,
so there are no pictures of that work in progress.
This picture is from after all the steps described below.

I got an adequately large sheet of felt.
Hobby Lobby is a chain where you can
select from a fairly wide array of color choices.
It's an odd place, in mid-August they had a lot of store area
dedicated to selling Christmas trees and other
Christmas decorations.
They're held up as some champion of Christianity,
but most of what they sell is manufactured in the
People's Republic of China where pretty much all
religion is suppressed.

Very important —
the adhesive used with the felt must not
be water based like Elmer's white glue!
That sort of glue is always releasing some water vapor,
either from the initial curing or from water that it has
absorbed from the air later.
Do not use Elmer's glue or similar
boiled-horses-based adhesives!

Right on the front of the can it lists some attributes
that suggest an entirely non-water-based nature:
• Extremely flammable
• Eye irritant
• Vapor harmful
• Harmful or fatal if swallowed

On the rear it lists
acetone,dimethyl ether,isohexane,
and
n-pentane
as ingredients.
It also claims to be useful on a wide array of material
including felt and plastics.

Yeah, this is the stuff.

Here's how I used it.
I did it a little at a time, working out from the center
and up from the cutouts:

Cut out an oversized rectangle of felt, more than
enough to cover the foam surface, including going
down into the cut-outs.
Make sure you have enough for that plus another
30 cm or so on all sides.
You might place the rectangle a little off-center,
and you will need at least 3 cm or so to stuff
down into the thin space between the foam and the
case shell.
Felt is cheap, make it big enough,
but not so big that it's hard to handle.

Put on another pair of rubber gloves.

Spray adhesive onto the floor and walls
of the central channel for the Garand.

Press the large rectangle of felt into place in
that channel, trying to get it into place so the
felt goes fully back into the floor/wall corner
in that channel.
You have something like 10-20 seconds to get this
done during the initial contact stage, so
work quickly!

Spray adhesive onto the flat "plateau" between the
Garand channel and the pistol pit(s) on one side only,
and down into those pistol pit floors and walls.

Press the felt into place throughout those pistol
pits, again making sure that the felt extends fully
into the floor/wall corners.

Repeat that for the pistol pit(s) on the other side.

Spray adhesive onto the "plateau" on one side of the
barrel continuing back on the same side onto
the surface between the pistol pit(s) and the
case rim.

Press the felt into place there.

Repeat for the other side.

Now trim the felt all the way around so you have something
like 3 cm hanging beyond the metal rim.

At this point you will realize two things.
First, you have accidentally glued the felt to the
aluminum rim of the case.
Second, given the poor structural integrity of felt,
you can pull it loose from just the rim while leaving
it stuck to the foam of the case.
So do that.

Now find a dull knife.
I used that big dull kitchen knife you saw earlier.
People who actually keep their knives sharp may need to
use something like a butter knife.

Use that large dull blade to work the felt fringe down
into the space between the foam and the case.

Continue that process all the way around.

You may need to do some extra trimming to work around things
like the nylon strap that stops the lid at about 90°
open.

You will also notice a few blobs of spray foam.
You can cleanly remove it from metal, as on the aluminum
case rim seen here, but that's about it.

I had to add a couple of spacer foam blocks, wrapped in
the dark red felt and glued to the lid,
to keep two of the pistols in place.
That side could have used a higher base level before
carving the cut-outs.

Starting weight:3.7 kg
(8.1571037 pounds) for the case as configured for a guitar.

Final weight:4.3 kg
(9.4798773 pounds) for the modified case with the added foam,
new latch, aluminum braces and felt.

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The reader MUST NOT attempt any reported activity, technique, or
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